Telephone message recording and reproducing apparatus



E. M. WILSON Aug. 1, 1933.

TELEPHONE MESSAGE RECORDING AND REPRODUCING APPARATUS Filed Feb. 24,,1950 Patented Aug. 1, 1933 UNITED STATES PATENT OFFICE TELEPHONE MESSAGERECORDING AND REPRODUCING APPARATUS Ernest M. Wilson, Portland, 0reg.,assignor to H. A. Hartshorn, Wm. F. Klinker, and Ernest M. Wilson, allof Portland, 0reg., as trustees Application February 24, 1930. SerialNo. 430,871

2 Claims.

changes in the conductors or instruments of the system; and also adaptedto be actuated by the normal call signal from the central station.

A further object of my invention is to provide an apparatus whereby torecord, for subsequent audible reproduction, both incoming and outgoingconversations between the subscribers to the telephone system, withoutaffecting the normal operation of the telephone system.

A further object of my, invention is to provide an apparatus whereby todeliver a conventional audible message into the substation telephonetransmitter, informing the calling party that my apparatus is connectedto the subscribers telephone, and the party calling maythus proceed tospeak his message in the usual manner, with assurance that the messagewill later be reproduced at the will of the party called.

Numerous telephone recording and reproducing devices have heretoforebeen made, but they have failed, according to my information,principally because they attempted to amplify the telephone currentitself for further recording and reproduction of the telephone message.Such attempts were unsuccessful because the electric current of theordinary telephone system is-weak, and is so distorted duringtransmission by passing through other fields of electrical influence orby the length I and various kinds of conductors used, which set up minoror secondary oscillations inthe current, and while such distortions donot affect the current sufficiently to change the frequencies at whichthe diaphragm of the telephone transmitter must vibrate to reproduce theoriginal voice sounds; any amplification of the current tends to at thesame time magnify these distortions so that the diaphragm of the soundreproducing instrument connected with the amplified current will alsoregister the minor and/or secondary oscillations set up in the current,and hence, will not reproduce the original voice sounds faithfully.

Therefore, a further object of my invention is to provide a telephonemessage recording and reproducing apparatus adapted withoutthe use ofexpensive microphones and special conductors and other auxiliaryapparatus to relay and transmit the oscillations of the weak telephonecurrent induced by the voice, to an amplified current in such a manneras to exclude the distorted or secondary oscillations of the'telephone'current acquired during its transmission through the telephone systemand relay only the oscillations induced by the voice to thus assure aclear and perfect recording and subsequent audible reproduction capableof being magnified to any tone volume desirable.

I attain my objects in a sound reproducing system, a telephone circuit,an amplifying element,

the strength of the current of the amplifying element being greater thanthe strength of the current of the telephone circuit, atransmittercomprising primary and secondary electro-magnets with adiaphragm therebetween, said electromagnets connected respectively withthe telephone circuit and the circuit of said amplifying element, thenumber of ampere turns of the primary and secondary electro-magnetsbeing respectively proportional to the ratio of the strength of thecurrents flowing through them to induce magnetic fields of substantiallyequal force, electrically operated switches actuated by the signalcurrent of the telephone circuit for connecting said primaryelectro-magnet with the telephone circuit and for closing the inputcircuit of said amplifying element, sound reproducing and recordingelements connected with said amplifying element, mechanical meansactuated by said sound recording elements for disconnecting said primaryelectro-magnet from the telephone cir- Fig. 1 shows a diagrammaticsideelevation of' my apparatus and illustrates by conventional symbolsthe circuits and telephone instruments of my apparatus, and illustratesthe mechanical construction and operation thereof: and

Fig. 2 shows a perspective detail of the mechanical means controllingthe operation of. the sound reproducing arm.

Referring now to Fig. 1, the usual connections with the central stationare shown at GN, Ll,'L2.

A manually operated switch a is provided for entirely cutting off theapparatus and the telephones from the central station.

The connections of the lines GN, L1, L2, with the telephone instrumentsare as usual, except for supplementary automatic relays and switchesplaced therein which comprise the line GN connected with anelectro-magnet b which operates a relay 0, the equivalent of the callbell in the ordinary telephone box. The line L2 passes through the usualcondenser d and induction coil e to the other side of the electro-magnetb and to a double, two-way, electrically operated switch 1, f. The lineL2 heredivides into lines aL2 and bL2, the line aL2 passing through theswitch 1" to a telephone receiving instrument h.

The line L1 passes through the induction coil e to the double switch 1,j where it divides into lines aL1, bLl, the line aLl passing through theswitch I to the receiver h and a transmitter i. The transmitter i isconnected directly by a line 0L2 with the line L2 by which the telephonecircuits are completed.

The foregoing describes the usual telephone connection, with what mightbe called the service telephone adapted, when the switch I is closed, tobe used independently of my apparatus for making an ordinary unrecordedcall.

For the telephone connections with my apparatus, the lines are asfollows: The line bL2 which passes through the switch 1 is alsoconnected with the receiver h and the line bLl is connected with boththe receiver 72. and transmitter 2'. The line dL2 through the switch Iis directly connected with L2 and the transmitter 2', thus thesecircuits are complete and since the switch 1, j is a double two-wayswitch, the lines aL1, aL2, and cL2 will be closed when the lines bLl,bL2 and dL2 are open and the reverse, hence, each set of circuits mayfunction independently of the other.

The double switch 7, f are operated by a double solenoid .9, comprisingelectro-magnetic elements 2, 3, having a common floating core 4. Theelement 3 is connected by a line 5 with a source of power 6 and with thesaid relay 0 by a line 50 which is operated by the electro-magnets b inthe line GN of the telephone circuits. The other side of the relay 0 isconnected by a line 7 with the source of power 6.

By this arrangement, the call signal from the central station closes therelay 0 and actuates the electro-maghetic element 3 of the solenoid sto'draw the core .4 towards it and thus close the switch f and open theswitch I; then the telephone lines bL2, etc., are connected with thecentral station.

The switch I also controls a line 10 connected to the line 5 and thesource of power 6 and an electric motor 11, which operates themechanical elements of my apparatus hereinafter described. The otherside of the motor 11 is directly connected with the power 6 through aline 12 to complete the circuit.

. The transmitting and amplifying element of my apparatus will now bedescribed.

The telephone lines bLl and bL2, which comprise the receiver circuit,are connected through tween the said magnets on each side the diaphragm.

The magnet 24 is connected through the lines 25, 25a with a suitableamplifier 26, which is connected with the source of power 6 through thelines 27, 27a. A manual switch 28 is placed therein, but the circuit isnormally closed at all times.

However, since the current of the amplifying element is stronger thanthat of the telephone circuit, and since the magnetic fields of each ofthe said electro-magnets must be equal in order to act equally on thediaphragm 24, I provide electro-magnets the respective numbers of ampereturns of which areequal to the ratio of the telephone current to that ofthe amplifying current, thereby providing magnetic fields of equalforce.

As before mentioned, even though the telephone current has becomedistorted by acquiring secondary oscillations from outside influences,such distortions are not registered by the diaphragm of the ordinarytelephone instrument, at its normal low voltage, but if the current isamplified, the distortions become so magnified that they are registeredby the telephone diaphragm and produce an imperfect reproduction of theoriginal voice sound induced in the telephone current. Further, suchimperfect reproduction becomes more pronounced on the more sensitivediaphragms of the so-called loud speakers, especially when the volume ofsound has also been magnified.

However, by the arrangement of the diaphragm 23 and the electro-magnets22, 24, as the magnetic field of the electro-magnet 22 is varied by theoscillations of the telephone current, the diaphragm 23 will vibrate tocorrespondingly vary the magnetic field of the electro-magnet 24, andthus only the oscillations of the telephone current induced by the voiceand which are the only oscillations registered by the diaphragm 23, willbe transmitted to the amplifier circuit 25, 25a and the secondaryoscillations or distortions, acquired during transmission from outsideinfiuences, will be excluded from the amplifier current 20, 20a, andhence the amplifier current may be amplified to produce a clear andfaithful reproduction of the original voice sounds in any volumedesirable.

The recording and reproducing elements of my apparatus are partelectrical and part mechanical and comprise a revoluble turntable 30driven by the motor 11, through a shaft 11a, on which a phonographrecording disc 32 is placed, and an annular supplementary, permanentreproducing disc 32a, circumscribing the disc 32 and havingrecorded-thereon a conventional message, to the effect that, This is thetelephone of J. Smith and is connected to an automatic recording andreproducing apparatus, please speak 3 our message clearly.

Of course, while I have shown the well known phonograph disc, any othersuitable recording device may be used, such as a cylindrical record asused in a dictograph, or a continuous strip or wire which is adapted forhaving sound grooves inscribed thereon.

Adjacent one side the turntable is provided a sound recording arm 35 ofsuitable construction, having in its base a sound reproducing instrument36, connected with the amplifier 26, through lines-36a, 36b, comprisingthe output circuit of the said amplifier, by which the messagereproduced from the amplifier will be inscribed on the disc 32.

A sound'reproducing arm 40 is arranged, for convenience, adjacent theother side of the tumtable and adapted to ride in the grooves of eachdisc 32, 32a and reproduce at the proper time the messages inscribedthereon, as hereinafter further described.

The motor 11 is also operatively connected by a belt 50, with a pulley51a carried on a shaft 51, on which are also mounted two similar pulleys51b, 510. The pulley 51b is connected by a belt 52 with a cam 53.

A vertically movable arm 54 is provided having a pin 54a adapted to bearon the said cam 53. A pendent arm 35a carried by the sound recording arm35 bears on a platform on said arm 54, so that, as the arm 54 is liftedby the cam as it rotates, the sound recording arm 35 will be raised andlowered from the disc 32.

The pendent arm 35a is also pivotally connected with a switch arm 70 ofa two-way switch 70a in the line 36b from the amplifier to the soundreproducing instrument 36 and a line '71 connected with another soundreproducing instrument '72. A line 72a connects the instrument 72 withthe line 36a of the output circuit of the amplifier and thus completesits circuit. By this arrangement, when the instrument 36 is connectedwith the amplifier, the circuit of the sound reproducing instrument 72will be opened and the circuit of the sound reproducing instrument 36will be closed and vice versa.

A tumbler 55 is pivoted to the free end of the arm 54, and normallysupports, in closed position, a switch lever 56 in a circuit formed by aline 58 connected with the line 27a and the power 6, and a line 59connected with the element 2 of the double solenoid s. The element 2 isalso connected through a line 59a with the line 12 and the other side ofthe source of power 6.

The lower end of the tumbler 55 is provided with a soft iron plate 55a,and an electro-magnet 61 is arranged so as to be adjacent theplate 55a,when the arm 54 is in its raised position.

The electro-magnet 61 is connected to the line 59 and a line 63a leadingto a switch arm 64 operatively connected with the adjacent end of thecore 4 of the double solenoid s. A contact point 65 is arranged adjacentthe said arm 64 and in contact therewith when the switch I is open, Thecontact point 65 is connected through the line 12 to the power 6. Theabove are the automatic circuit opening and closing elements of myapparatus and will be again referred to.

The said sound reproducing arm 40 is mounted at its end on a rotatableand longitudinally movable shaft 80, which rests at its lower end on alongitudinally, horizontally, movable arm 81. The arm 81, see Fig. 2, isprovided with a beveled surface 81a at one end and is so arranged thatits other end bears against a cam 83, driven by a belt 84 passed overthe said pulley 510. An expansion spring 810 holds the arm 81 in contactwith the said cam 83, and a hook b carried by the shaft 80 is engageablein an elongate slot 81b in the arm 81, so that the rotation of the cam83 will, at the proper time, move the arm 81 longitudinally and causethe end of the shaft 80 to ride up or down on the beveled surface 81a;and at the same time the hook 80b in the slot 81b will cause the shaftto rotate. and thus swing the arm 40 in a horizontal plane and raise itfrom or'lower it onto the said disc 32a for the delivery at thepropertime of the said conventional message.

A circuit 40a of the sound reproducing arm 40 is connected through amake and break switch 41, with the lines 25, 25a of the input amplifiercircuit which is adapted to be closed only when the arm 40 is bearing oneither of the discs 32 or 32a.

In the operation of my apparatus, the switch 1" being normally closed,the telephone may be used as usual by merely lifting the receiver h fromthe hook, not shown, by which central is called, and using thetransmitter i and receiver h, to carry on the usual conversationindependently of my apparatus. Also to connect the telephone circuitswith central, so that they will function as an ordinary telephone,independently of my apparatus, for incoming calls, I

have provided a double manual switch 1- in the line GN to divert thesignal current from the passing through the electro-magnets b and carryit around the said relay 0 through a line aGN having an ordinary callbell t, connected therein.

For the receiving and recording of an incom ing message, the call signalfrom the central station through the line GN will actuate theelectro-magnets b to close the relay c and the circuit 5 through theelement 3 of the solenoid s, which will close the switch 1 and open theswitch I, thus closing the circuits 10-, 12 through the motor 11 and thelines bL1, bL2, and dL2 of the telephones.

The motor 11 will then be actuated to rotate the turntable 30 and thecams 53 and 83 also driven by the motor 11, but at a reduced speed.

At this time both the sound recording arm 35, and sound reproducing arm40 are raised from the discs 32, 321;, being held so by the previouslyadjusted positions of the cams 53, 83. As-the cam 83 rotates, the end ofthe arm 81 willride into the low surface 83a and cause the arm 40 to belowered onto the disc 32a closing the switch 41 in the circuit 40a tothe amplifier 26, whereby the conventional message inscribed thereon,will be reproduced through the amplifier and sound reproducinginstrument '72 into the transmit er i.

By the tim the conventional message is finished the cam 83 will haverotated until the arm 81 rides out of the low place 83a, and the arm 40is lifted. At this time, the cam 53 being previously so positioned willhave rotated until the pin 54a of the arm 54 rides off the high place53a on the cam 53, and the sound recording arm will then be-lowered ontothe disc 32 to record the message which will be spoken in reply to thesaid conventional message through the circuit 20, 20a, 25, 25a and theamplifier 26.

At this time, of course, the switch 70a is positioned to close thecircuit 36a, 36b of the inthe apparatus from the telephone system andstop the motor 11, simultaneously.

Further, as the arm 54 is raised, the soft iron plate 55a on the tumbler55 is positioned adjacent the electro-magnet 61, the circuit of whichhas been closed by the movement of the solenoid s and operation of theswitch arm 5&1, so.

electro-magnet 61, which, as before mentioned, is

also connected in the circuit 59.

Then, when it is desirable to reproduce the message so recorded, aclutch 92 on the motor shaft is disengaged so that only the turntable 30will be driven and a-switch q in the circuit 10 and 12 of the motor 11is closed to actuate the latter.

The sound reproducing arm 40 is then manually lowered on the disc 32 bymeans of a rotatable-cam disc 39, which, when rotated, permits thearm 50to move downwardly on the shaft 80, and disengage itself from a lockinglug 39a on the upper end of the shaft 80 so as to swing freely thereon.

Thus the arm 40 will be lowered onto the disc 32, and the switch 70a inthe circuit 71, 72a of the sound reproducing instrument 72, beingclosed, since the arm 35 is raised the message will be reproducedthrough the amplifier 26 and the sound reproducing instrument 72.

When the message has been reproduced the sound arm 40 is lifted by thecam disc 39 and re-engaged with the locking lug 39a, the switch qopened, and the clutch 92 put in engaged position again. The old disc 32may then be removed and replaced by a new one, the old being retainedand filed as a matter of record, which could again be reproduced on myapparatus or any suitable phonograph.

Further, should a conversation be in progress over the telephone,independently of my apparatus, and it is desirable to have both sidesrecorded, the said clutch 92 will be disengaged and another cam disc 93carried by the arm 54, which bears on the pin 54a, will be rotated so asto permit the pin 54a to lower the sound recording arm 35 onto the disc32. Then a manual switch p in the circuit 5a, 7, is momentarily closedto cause the element 3 of the solenoid s to be actuated to close theswitch I and connect my apparatus with the telephone system and actuatethe motor 11 so that the message will be recorded through the circuits20, 20a, the electro-magnets 22, 24, and the circuits 25, 25a to theamplifier 26, which is connected to the sound reproducing instrument 36at the base of the sound recording arm 35.

At this time a hose-like element 90, provided with an ear piece leadingfrorn the sound box of the sound reproducing instrument 36 is preferablyused as a receiver, since the person listening will then hear positivelythe message being re corded.

The outgoing conversation through the transmitter is also recorded,-because both the circuits of the receiver h and transmitter i, are, asusual,

When the conversation is finished the cam disc 93 will be rotated tolift the sound recording arm 40 which will close the switch 56 andautomatically actuate the element 2 of the solenoid s to open the switchj and close the switch I, as before mentioned. Also, the clutch 92 willagain be engaged and the apparatus will again be ready for automaticallyreceiving and recording a call from central, since the relativepositions of the cams will not have been altered, and the correspondingoperations of the arms 35 and 40 not changed.

Of course, in actual practice, it would be desirable to provide suitablemechanical means, whereby the disengaging of the clutch 92, the rotationof the cam disc 93, and the momentary closing of the switch 10 may bedone simultaneously in one operation.

I claim:

1. In a sound reproducing device the combination of a transmitter and anelectric telephone circuit in which the transmitter is connected, areceiver and a second .electric circuit in which the receiver isconnected, an amplifying element in the second circuit, and a relay.element adapted to transmit substantially only the oscillations inducedby the voice in the said first circuit, said relay element comprisingelectromagnets connected in said circuits respectively and a diaphragmbetween said magnets, the strengths of said magnets being relativelyproportioned to induce magnetic fields of substantially equal force onboth sides of the diaphragm, means actuated by the signal current of thetelephone circuit for connecting the latter with its electro-magnet,sound reproducing means and recording elements connected with saidamplifying element, mechanical means actuated by said sound recordingelements for disconnecting the electro-magnets from the telephonecircuit and said amplifying element. 7

2. In a sound reproducing device the combination of a telephone circuit,and an amplifying circuit, a relay element connecting said amplifyingcircuit and said telephone circuit, said relay comprisingelectro-magnets connected in said circuits respectively and a diaphragmbetween said magnets, means actuated by the signal current of thetelephone circuit for connecting the latter with its electro-magnet,sound reproducing and recording elements connected with said amplifyingcircuit, mechanical means actuated by said sound recording elements fordisconnecting the electromagnets in the telephone circuit and theamplifying circuit.

ERNEST M. WILSON.

